This invention relates to an automatic chemical analyzing method and apparatus and more particularly to an analyzing method and apparatus in which a liquid sample and a reagent are successively poured into a plurality of cuvettes conveyed discretely, the optical characteristics of the reacting solutions in the cuvettes being automatically measured.
According to most conventional chemical analyzing methods used especially in hospitals for clinical examination, a certain quantity of a sample to be measured is put in a reaction vessel or a cuvette and reagent is added to the sample so as to cause a chemical reaction to take place, colorimetric measurement or rate assay measurement is performed by using a spectrophotometer, and the concentrations of the constituents or other factors in any specified unit are derived as an analyzed result from the result of the previous measurement. Examples of such an analyzing method are U.S. Pat. No. 4,025,311 where a reaction chamber is used, and U.S. Pat. No. 4,158,545 where conveyed cuvettes are employed.
In an automatic chemical analyzing apparatus including the above examples, which performs the measurement operations automatically, it is customary for each measurement cell or cuvette to be used repeatedly. In such a case, even if each cuvette is cleaned every time after use by way of the cleaning operation comprising part of the analyzing process, fatty components contained in the sample will gradually increase the opacity of the cuvettes light-permeable surface and such opacity will, contribute to measurement error. Also, flaws in the light-permeable surface of the cuvette will lead to measurement error. Further, since the photometers output causes zero drift phenomenon due to fluctuation of the luminosity of the light source and changes in the characteristics of the optical system, the detectors and the electric circuitry, the measured value adversely fluctuates with the lapse of time so that the difference between the initially measured value for the blank and the measured value fluctuates.